Molecular Analysis of the Developmental and Hormonal Systems Regulating Fruit Ripening

The ripening and development of fleshy fruits is regulated by environmental, hormonal and developmental cues. Ethylene is the key ripening hormone of climacteric fruits and can influence ripening in many non-climacteric fruits. Our laboratory uses tomato as a model system to understand ripening regulation and has identified a number of necessary ripening genes via positional cloning of loci underlying ripening mutations and transcriptional profiling studies of ripening associated gene expression. To date we have identified six transcription factors that we have shown to be necessary for tomato fruit ripening via transgenic studies including two MADS-box, an Ethylene Response Factor (ERF) and an APETALA2 gene homolog. One of the MADS-box genes, TAGL1, is especially intriguing in that it suggests a molecular link between fleshy fruit development and eventual ripening via a single gene product. A summary of these gene activities in the context of other reported regulatory and ethylene response genes will be presented.